Floc concentration tank



Jan. 6, 1942. M. B. TARK FLOC CONCENTRATION TANK Filed Oct. 14, 1958 Jan. y6, 19H42. v M, B, `TARk 2,268,726

FLOG CONGFIITRAT10Nv TANK Filed oci. 14, 193s 4 2 sheets-sheet 2 Patented Jan.e,1942

azesnzs FLoc CONCENTRATION TANK" A Marcus B. Tai-k, Philadelphia, Pa., assigner to Link-BeltCompany', Chicago.' lll., a corporal non of minors Appuaoa october' 14, 193s, semi No. 234,912 zo claims. (ci. 21o-1s) My invention` relates to apparatus for` the treatment by flocculation and sedimentation of liquids containing solids or colloids. or both insuspension or solution. It has for one object to provide an apparatus suitable to carry out a continuous process whereby in one organized mechanism liquids either with or without chemical dosagefmay be occulated or coagulated and the flocs may be precipitated out so that a clarified eilluent may be'obtained and so that a concentrated sludge may be withdrawn. j

Another object of the invention is to provide means to insure that the maximum possible proportion of solids and colloids may be -removed Vfrom the liquid. l

Other objects will appear from time to time throughout the specification and claims,

My invention is illustrated more or less diagrammatically in the accompanying drawings,

wheren- Figure 1 is 'a plan view; e

Figure 2 is a section along the line 2-2 of Figure 1; A

Figure 3 is a section along the line 3-3 of Figure 2.

Like parts are indicated by like characters throughout the specification and drawings.

I is a cylindrical sedimentation or settling tank, though other suitable shapes may be used.

having a oor 2, vslightly inclined downwardly from the periphery toward the center, though the inclination may be varied or. the oor may even be horizontal. 3 is an annular sludge hopper encircling butspaced from the center of the tank, though. the hopper may be of dierent shape or arrangement. 4 is an' influent pipe beneath the floor 2, of the tank and discharging through any suitable means as the elbow 5, into the tank at the bottom. 6 is a conical wall extending upwardly from the bottom of the tank concentric with and communicating with the el- 'bow 5, and outwardly ared or expanded.- The wall 6 terminates in an upwardly extending annularwall 1, which extends above the level of the liquid in the tank. i

The liquid level is controlled by the etlluent Weir 8, so that the liquid entering the tank through the pipe I, the elbow 5, into the .upwardcommunicating with an eilluent pipeIZ. AI3 is a deilector or baille plate mounted on the wall 1,

and masking thev outlet ports 0 so as toinsure an even distribution of the. eilluent as it is discharged from the ilocculating chamber 9, into the sedimentation chamber Il, within the tank I, and encircling the flocculating 'chamber 9.

The outletports I0, may be continuous or as,

in the preferred form evenly spaced about the entire periphery of the wall 1. |5 is a sludge discharge pipe leading from the sludge hopper 3, outwardly beneath the floor of the tank.'

I6 is a i'lxed bridge supported upon the wall 1, and extendingv across the center of vthe tank. T his bridge supports a turntable I1, upon which is rotatably mounted the inner end of a traveling or rotating bridge I8. The bridge is supported at its outer end on wheels-I9, traveling along the track 20, on the'outer periphery of the tank I,

so that access may be had to the xed bridge Iiiv and the machinery associated with it by means ofthe rotating bridge I8. l

2| is a high speed central shaft supported at its lower end in a bearing 22,.adjacent the bottom of the flocculating chamber 9, extending upwardly to the bridge I6. 23 is an intermediate speed hollow shaft encircling the shaft 2|, having abearing 24 thereon at its lower end and extending upwardly to the bridge I6. 25 isa low speed shaft extending upwardly to the bridge I3. 21 is a high speed paddle mounted on the high speed shaft 2|, at the bottom of the occulating chamber. 231s an intermediate speed paddle, mounted on the hollow shaft 23, intermediate the top and bottom of the ilocculating chamber. 29 is a low speed paddle mounted on the shaft 25, adjacent the top of the flocculating chamber. I

The shafts 2|, 23 and 25, concentric one with another are positioned at the top by a bearing 30, there being bearing members inside the shaftsso that they are free to rotate with respect one to another. 3| is a miter gear on the upper end ly expanded flocculating chamber 9, dened by'.

the conical wall B, and the annular wall 1, may pass outwardly into the body of the tankfl,

through a series of evenly spaced outlet` ports I0, and thence may flow radially to discharge .over-v thewelr. Y II is an annular trough encircling theweir 3,

by a chain 38,.over the sprockets 39 and III, and

driven by a motorized speed reducer 4|, on the bridge l5. The relative diameters `of miter gears and pinions are selected so that the speed of rotation of the inner shaft is a maximum and of the outer shaft is a minimum and of the intermediate shaft is between the two sov that the.

lower paddles rotate mercy-rapidly than the inon a bracket 45, depending downwardly from the bridge Il. 4I isa drive pulley over which the chain 42 travels. The idler pulley 4l guides the chain as it comes up out of the trough to the drive pulley 46. I'he chain after it has passedover the trough pulley is slack and no guide means are needed to insure its return to the trough.' 'Ihe drive pulley 4i is mounted on a shaft 41, which is driven by means or chains 4I, and sprockets 49 and Il, by the motorined speed reducer 5|. This motor rotating the shaft 41, causes the bridge to 'rotate about its pivot point by exerting atension on the chain, the friction of the chain on the walls and noor of the eiiluent trough I i being sumcient to drive the bridge.

52 is a sludge collector ladder. It is supported by the framework 53, from the bridge il, and the ladder and framework carry idler sprockets 54, 55, and drive the sprocket I6 over which travels the conveyor chain 51. 'I'his chain carries a plurality or conveyor nights 54, the nights being supported on the ladder I2, at a point sufncient to Just clear the noor on the tank. They may be equipped with rubber or other squeegee vblades 58, to insure that the nights as they move inwardly along the ladder 52 will scrape settled sludge from the bottom of the ntank. The sprocket Si is driven by chain il, and sprockets Il, 6l and miter gears 6I, 62 from the shaft 41, so that `whenever the bridge Il travels about the tank, the sludge collecting nights will move inwardly toward the center of the tank in unison there.' with. 63 is a sludge plow carried by the ladder 52, at one side of the path of the nights Il, so that as the nights are lmoved into the settled sludge. the sludge is moved inwardly by the `nights and kept in the path of the nights by the sludge ploy 63, which extends radially from the outer periphery ofthe settling tank to the noccu- -lation tank. 64 is a rotating cover for the sludge hopper 3. It is connected to the sludge plow and as the sludge plow travels around the rotating cover also rotates. This cover is apertured in line with the sludge collecting ihts so that as the sludge is red centrally by the nights, it is discharged into the sludge hopper but there is no sludge deposition and no escape of sludge from the hopper at any other point except sludge pipe beneath the noor o! the course, be oi any other shape. 'I'hey are not necessarily concentric. They might even be sep-A arately located side by side.

I have shown the mixing chamber as being conical and terminating in a cylindrical portion. 75

It might be other than conical and the cylindrical portim might be dispensed with. I have shown the wall of the cylindrical portion extending upv wardly above the liquid level. In enect, it is a weir and its purpose is to provide an 'adequate space for the now at low'velocity, of the mixed and nocculated liquid containing large nocs from the mixing chamber into the settling chamber at such rate or speed that the nocs will not be broken up and will settle rapidly and easily in the sedimentation chamber.

l1, 61 are bleeder valves controlling ports II.

in the wall oi the mixing chamber. 'I'hey communicate directly with the sedimentation or settling rchamber and their purpose is to permit running on oi additional noc from below the normal noc blanket at the top of the mixing chamber ii there should at any time be too great a concentration of noc. Such noc being discharged into the sedimentation chamber at a point iar below the liquid level and adjacent the center, will, of course, settle and be carried out with the remaining noc, settled as sludge, which entered from the normal outlet ports.-

The use and operation of my invention are as l follows:

'rne uquid news upwardly through the mixing chamber at gradually reduced speed owing to the upward expansion of the chamber and is agitated and mixed in the intermediate zone though less violently than in the preliminary mixing zone.

Asthe liquid continues its upward now it reaches the zone of maximum cross'sectional area of the nocculating chamber where it encounters a sludge blanket formed by gradually accumulatingl and .coagulating nocs from the liquid. 'This blanket is constantly renewed by the addition of nocs from below and there is a constanty discharge' of large nocs from the upper portion of the blanket accompanied by the liquid which has been strained through the blanket.

The nocs commence to form, probably as pin nocs, localized in the liquid as itenters the system. The violent agitation mixes the sewage and chemicals and promotes the formation of more pin nocs throughout the entire mass. Then as the agitation decreases in consonance with the upward now at gradually decreasing velocity of the liquid larger and larger nocs are formed until the noc blanket is reached wherethe remaining small nocs are combined with the larger ones to form the relatively thick blanket oi relatively large coagulated particles or nocs.

'I'his noc blanket remains generally constant vin thickness and density because the large nocs which now on with the liquid are constantly being replaced by nocs from below.

These large nocs pass d own around the outer periphery of the mixing 'or nocculating chamber into the sedimentation chamber below the encircling baille. 'I'he velocity or now is materially reduced and the liquid in the sedimentation 'chamslow and uncontrollable.

ber is in a substantially quiescentcondition. Thus those. flocs which have been initially discharged into the sedimentation chamber from beneath the baille tend to settle out, the clariiled liquid flowing over the eiliuent welr.

The iiocs which settle as sludge on the floor of the sedimentation 'chamber are collected by the sludge plow and the flight conveyors as the sludge plow rotates about the center of the tank and the flight conveyors move inwardly toward the center. The sludge thus collected is discharged into the opening through the annular cover of the sludge hopper and thence withdrawn through the sludge pipe. Since the annular cover is connected to the sludge plow, it rotates with it. The sludge hopper is always closed except at the point where it receives the sludge discharged from the flight conveyor.

If the floc blanket should become too thick, and extend down too far into the fiocculating or mixing chamber, the bleederl ports in the wall of the flocculating chamber may be opened to permit' more of the ocs to flow directly into the sedimentation chamber far below the surface of the liquid. 'Such flocs will be free to settle in the quiescent body of liquid in the sedimentation chamber and will be carried ofi as sludge just chamber through the distribution ports at the top of the mixing chamber.

tlme'to time. 1 v

My apparatus while it takesadvantage of the flow of the liquid. fat the same time superimposes upon it a controlled rate of agitation and stirring so that proper flocculation always takes place and so that the sludge blanket niay be continuously formed and renewed. The violent agitation at the bottom of the tank promotes the necessary mixing and the progressively decreasing violence of agitation as the material i'lowsvupwardly permits the ocs to contact one anothervand coagulate and the rate of agitation 4 out breakage to the sedimentation tank.

. as are the flocs which enter the sedimentation The treatment of sewage by flocculation or coagulation is of long standing. Experience has taught that under some circumstances, especially when very ii'ne solids or colloids are in suspension. merely arresting the flow of the liquid in a quiescent body is not suiilcient to permit adequate clarification by sedimentation because the material is so nely divided thatit will not settle out in areasonable length of time.

be resorted to.

Flocculation or coagulation means applying some kind of treatment tothe liquid which wl cause the fine materials therein' to be concentrate ed or accumulated and form large ocs which will settle out. l

. Sometimes this coagulation may be effected by agitation alone. In other cases, it is necessary to provide some additional material with which the sewage tion.

An important step in the treatment of sewage liquids by fiocculation isthe formation somewhere in the system of a floating iloc blanket through which the liquid may pass.-

The effect of Vsuch a lloc blanket is to strain out the fine, substantiallyunsettleable ocs from the liquid, and to permit theliquid to carry away intov the sedimentation or settling zone only flocs large enough for effective settling.

Such a blanket is an exceedingly delicate thing. If the velocities are too low, it will settle out. If the velocities are too high, it 4will be broken up or carried away. Suitable velocities are within a range of one to five feet per minute. Some kind of agitation is essential because the small ocs must be moved about and brought into contact with one another so that they may agglomerate to form large flocs. Without stirring or mixing or agitation the flocculating eiect is exceedingly breaks the fiocs up. I

If the flow of current of the liquid being treated alone is "relied upon, trouble is likely to ensue y K l When this is the case, occulation 'or' coagulation must' may be dosed to promote floc forma'-` Too much agitation The mixing paddles I have shown are merely .examples of a suitable type of agitating means.

Other agitatlng devices might be used. Water jets or air diusers, other types of paddles, any andall of' them can be used and are well-,known in the art as being used to provide the agitation necessaryV for flocculation of sewage and similar materials according to my invention. I wish, therefore, that my showing be regarded as in a sense diagrammatic and not limited tothe spe- Y ciflc 4mechanical details disclosed.

While my invention is illustrated by a con-` crete upwardly expanding ilocculation chamber,

-obviously it may be made of any other suitable material, wood, sheet metal or the-like.` While I have shown a cylindrical wall extending upwardly from the point of maximum diameter of .the cone, the wall is primarily a structural element. The device might very well operate ifv this wall were omitted and the liquid were allowed to flow over the upper edge of the cone into the sedimentation chamber, the essential thing in that respect being that the area through which the liquid and-ocs travel from the fiocculation to the sedimentation chamber is large enough so that the flow will be exceedingly gentle whereby the ilocs are not broken as they travel from one .chamber tothe other.

1. Apparatusl for clarifying liquids including av fioc concentration chamber, means for passing liquid `through y,said chamber, mechanical means for agitatlng and mixing the liquid and for form- 1 ing a blanket of iloc particles within the chamber and means for withdrawing liquid from the chamber after it `has passed through the blanket and for withdrawing ilocs from the upstream' portion of the blanket, means for settling the floc out of said liquid-and for collecting the ocs thus settled.

2'. Apparatus for clarifying liquids including a iloc concentration chamber, means for passing liquid through said chamber, means independent of the rate of flow vof liquid through. the chamber for agitatlng and mixing the liquid ancly for forming a blanket of` floc particles within the chamber and means for withdrawing liquid from the chamber after it has passed through the blanket and for withdrawing ficos from the upbecause ordinarily the ow ratechanges from stream -portion of the blanket, means for settling the floc out of said liquid and for collecting the flocs thus settled.

3. Apparatus for clarifying liquids including a floc concentration chamber, means for passing liquid through said chamber, means independ- `ent of the rate `of flow of liquidthrough `the means within the sedimentation chamber for collecting material settled therein.

4. Apparatus for clarifying liquids including a iioc concentration chamber, means for passing liquids therethrough, a plurality of stirring paddles in the chamber in the path of the liquid, means for operating the .upstream paddle at relatively high speed, the downstream paddle at .relatively low speed and the intermediate paddle at intermediate speed.

5. Apparatus for clarifying liquids including a floc concentrationchamber, means for passing liquids therethrough the cross sectional area of thechamber increasing in the direction of such liquid iiow, a plurality of stirring paddles in the chamber in the path of the liquid, means for operating the` upstream paddle at relatively high speed, the downstream paddle at relatively low speed and the intermediate paddleL at intermediate speed.

6. Apparatus for clarifying liquids including a floc concentration chamber, means for passing liquids therethrough, the cross sectional area of the chamber increasing in the direction of such liquid flow, means within the chamber independent of the rate of flow of liquid therethrough for imparting to the liquid an agitation the violence of which decreases in the direction f ow.

7. Flocculation apparatus including an upwardly expanding flocculation chamber having an influent opening at the bottom and an effluent opening at the top, means for agitating the liquid as it flows upwardly through the chamber.

8.' Flocculation apparatus including an upwardly expanding flocculation chamber having an infiuent opening at the bottom and an effluent opening at the top, mechanically operated means for agitating the liquid as itflows upwardly through the chamber.

9. Flocculatlon apparatus including an upwardly expanding flocculation chamber having an infiuent opening at the bottom and an ellluent opening at the top, means for agitating the liquid as it flows upwardly through the chamber, said means being adapted toimpart to the liquid, an agitation the intensity of which decreases in the direction of travel of the liquid.

10. sedimentation and fiocculation apparatus including an upwardly expanding occulation chamber having an inu'ent opening at the bottom and an efuent opening at the top, and means for agitating the liquid as it flows upwardly through the chamber, and a sedimentation chamber encircling the fiocculatlon chamber, there being a plurality of effluent apertures between the flocculation and the sedimentation chamber.

11. sedimentation aind iiocculation 'apparatus including an upwardly expanding occulation chamber having an influent opening at the bottom and an eiiiuent opening at the top, means for agitating the liquid as it ows upwardly through the chamber, said means being ladapted to impart to the liquid, an agitation the intensity of which decreases in the direction of travel of the liquid, and a sedimentation chamber encircling the flocculation chamber, there being a plurality of efiiuent apertures between the flocculation and thesedimentation chamber.

x12. sedimentation v'and flocculation apparatus including an upwardly expanding ildcculation chamber having an influent opening at the bottom and an eiiluent opening at the top, and means for agitating the liquid as it flows upwardly through the chamber, and a sedimentation chamber encircling the ilocculation chamber, there being a plurality of effluent apertures between the flocculation and the sedimentation chamber, and means for mechanically collecting settled sludge from the sedimentation chamber.

13. An apparatus for clarifying liquids including a oc concentration chamber, means lfor passing liquid therethrough, mechanical means in the chamber foragitating and mixing the liq'- uid and for forming and locating a blanket of floc particles extending substantially completely across the line of now of the liquid, asedimentation chamber, means for continuously withdrawing liquid, containing floc, after it has passed entirely through the floc blanket, from the floc concentration chamber and discharging it to -the sedimentation chamber, and manually controllable means for withdrawing iioc from the upstream side of the iioc blanket and separately' discharging such oc to the same sedimentation chamber.

14. Anapparatus for clarifying liquids including a generally cylindrical sedimentation chamber, an -eliluent passage discharging therefrom, a iloc concentration chamber extending upwardly from the center of the oor, of the sedimentation chamber, out of contact with the Walls thereof, and increasing in cross sectional area from the bottom upwardly, an influent pipe adapted to supply liquid to the bottom of the floc concentration chamber,. a connection between the upper portions of the two chambers, a sludge hopper in the floor of the sedimentation chamber, encircling the iloc concentration chamber, mechanical means for collecting and propelling settled sludge toward and discharging it into the sludge hopper, a plurality of agitating paddles arranged one above the other extending from the bottom of the floc concentration chamber upwardly, means for separately rotating each paddle at a speed less than the speed of rotation of the one below it, there being a free and substantially unobstructed passage upwardly from each paddle to the next one.

15. An apparatus for clarifying liquids including a generally cylindrical sedimentation chamber, an vetliuent passage discharging therefrom, a floc concentration chamber extending upwardly from the center of the floor of the sedimentation chamber, out of contact with the walls thereof, and increasing in cross sectional area from the bottom upwardly, an influent pipe adapted to supply liquid to the bottom of the floc concentration chamber, a connection between the upper portions of the two chambers, a sludge hopper in the floor of the sedimentation chamber, encircling the floc concentration chamber, mechanical there being a free and substantially unobstructed passage upwardly fromv each paddle to the next one, and' manually controlled means for discharging iioc from the oc concentration chamber into the sedimentation chamber at a point below the connection between the upper portions.

16. An apparatus for clarifying liquids including a 'oc concentration chamber, means for passing liquids therethrough, a plurality of paddles in the chamber in the path of the liquid, and

means for rotating them in planes perpendicularl to the line of travel of the liquid through the chamber, therebeing a free and substantially unobstrutced passage from one paddle to the next one, means for rotating each paddle at a speed less than the speed of the adjacent upstream paddle, the low-speed paddle and the walls of the chamber dening an area wherein the liquid is relatively quiescent to form and locate a iioc blanket, and means for withdrawing the floc containing liquid from the chamber after it has passed through said blanket.

17. An apparatus for clarifying liquids including a oc concentration chamber and a sedimentation chamber, means ior passing liquid first through the floc concentration chamber and then through the sedimentation chamber, means in the path of the liquid in the floc chamber for agitating and mixing the liquid and for forming and maintaining a blanket of iioc particles extending substantially entirely across the line oi flow of the liquid through the iloc chamber, the liquid after it has passed through the floc blanket being adapted to pass into the sedimentation chamber. v

18. An apparatus for clarifying liquidsincluding a oc concentration chamber and a sedimentation chamber, means for passing liquid iirst through the iioc concentration chamber and then through the sedimentation chamber, means inthe path of the liquid in the iloc chamber for agitating and mixing the liquid and for forming and maintaining a blanket of floc particles extending substantially entirely across vthe line oi flow of the liquid through the iloc chamber., the liquid after it has passed. through the floc blanket being adapted to pass into. the sedimentation` chamber, and manually adjustable means for withdrawing iioc from the up-'stream side of the fioc blanket and discharging it vseparately into the sedimentation chamber.

19. A sedimentation and occulatlon apparatus including an upwardly expanding'occulation chamber having an influent opening atthe bottom and an etliuent opening at the top, means independent of the flow of liquid through the chamber for agitating the liquid as it ilows upwardly through the chamber, said means being adapted to impart to the liquid, an agitation the intensity of which decreases in the direction of travel'of the liquid, and a sedimentation chamber encircling the occulation` chamber, a liquid connectionv between the ilocculation and the sedimentation chambers.

20. A fiocculation apparatus including a nocculation chamber, means for passing liquid therethrough, the chamber increasing in cross sectional area in the direction of lliquid flow, a sedimentation chamber, a direct and unobstructed connection between the two chambers, means for forming and maintaining a continuous oc blanket in the occulation chamber extending substantially entirely across the chamber, whereby all of the liquid passing through the chamber is constrained to flow through the oc blanket, said'means including means for agitating the MARCUS B. TARK. Y

liquid independent of the ow of liquid throughv 

